1. Field of the Invention
The invention relates to a sheet guide device for guiding a sheet passing along an intersecting sheet guide path, and an image forming apparatus provided with the sheet guide device in the apparatus main body thereof and in which a sheet having an image formed thereon is guided by the sheet guide device.
2. Description of Related Art
In recent years, image forming apparatuses such as a copying machine, a printer, a facsimile apparatus and a compound machine of these have spread, and these image forming apparatuses are of a construction in which the copying machine is the basis. However, owing to the recent rapid spread of personal computers, a construction in which the printer is the basis are becoming the mainstream of the image forming apparatuses. Also, in the image forming apparatuses, two-side printing in which images are formed on the two sides of a sheet has become popular from the viewpoints of environmental countermeasures, the saving of natural resources, etc., and many kinds of machines have become provided with a duplex image forming function.
FIG. 8 of the accompanying drawings is a schematic cross-sectional view of a printer, which is an example of a conventional image forming apparatus taken along a sheet transport direction.
The printer 121 shown in FIG. 8 is such that in an apparatus main body 123, a toner image is transferred to a sheet P fed from a sheet feeding portion 101 in an image forming portion 102, and the sheet is passed through a fixing device 103 to thereby fix the toner image on the sheet. Then, the printer 121 selectively delivers the sheet having had the toner image fixed thereon to a face-down tray (hereinafter referred to as the “FD tray”) 106 and a face-up tray (hereinafter referred to as the “FU tray”) 105 or transport the sheet to a surface reverse transport path 119, by a combination of a transport path switching gates 111 and 112.
The sheet fed into the surface reverse transport path 119 is switch-back-transported and has its front surface and back surface reversed by the surface reverse transport path 119. The sheet is then transported along a duplex transport path 120 and is again supplied to the image forming portion 102, whereby a toner image is formed on the other side of the sheet. Thus, the toner images have been formed on the two sides of the sheet. The sheet having had the toner images formed on the two sides thereof is finally selectively delivered to the FD tray 106 and the FU tray 105.
FIG. 9 of the accompanying drawings is a schematic cross-sectional view of a printer, which is another example of the conventional image forming apparatus taken along a sheet transport direction.
The printer 122 shown in FIG. 9 is also such that in an apparatus main body 124, a toner image is transferred to a sheet P fed from a sheet feeding portion 101 in an image forming portion 102, and the toner image is fixed by a fixing device 103. The printer 122, when it forms an image only on one side of the sheet, delivers the sheet to the FD tray 106. The printer 122, when it is to form images on the two sides of the sheet, once guides the sheet toward the FD tray 106, and thereafter reverses the rotation of a pair of reverse rollers 116 and reversal-transports the sheet to thereby transport the sheet to a duplex transport path 120. The sheet is transported along the duplex transport path 120, and is again supplied to the image forming portion 102, whereby an image is also formed on the other side of the sheet. Thus, the images have been formed on the two sides of the sheet. The sheet having had the images formed on the two sides thereof is finally delivered to the FD tray.
However, the printers, which are the conventional image forming apparatuses, have caused the following problems.
The printer 121 shown in FIG. 8 has a space and construction exclusively for reversing the sheet going toward the duplex transport path 120 and therefore, the space particularly in the height direction of the apparatus main body 123 of the printer 121 becomes large, and this has led to such problems as the increased cost of a frame construction, etc., the aggravation of operability and a further increase in cost by parts for exclusive use.
The printer 122 shown in FIG. 9 is a mechanism which solves the problems peculiar to the printer 121 shown in FIG. 8, and effects the reversal of the sheet going toward the duplex transport path 120 by a transport path 125 leading toward the FD tray 106. However, the transport path 125 leading toward the duplex transport path 120 is disposed on the left side of the apparatus main body 124 and therefore, there is not a transport path leading toward a tray corresponding to the FU tray 105 shown in FIG. 8 and thus, the FU tray cannot be provided. That is, there has arisen the problem of a reduction in a specification called the curtailment of a delivery port.